What's the deal with chart analysis?

Well, I'm brand new to chart analysis and I'm testing out strats and theories @ investopedia...but one thing I can't wrap my head around is chart analysis. How are shapes and figures in charts a reliable way to analyze the potential performance of a stock?

You've got to mix technical analysis with tape reading, market sentiment analysis, economic analysis, a little dose of contrarian analysis, and some basic fundamental knowledge of credit cycles to be able to trade consistently. Using charts alone is 50/50 in my opinion. I use it only as one tool in a toolbox.